Bit-rate control in a multimedia device

• US 6,704,281 B1
• Filed: 01/13/2000
• Issued: 03/09/2004
• Est. Priority Date: 01/15/1999
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Ojala, Pasi, Luomi, Marko, Hourunranta, Ari
• Primary Examiner(s): Yao, Kwang Bin
• Application Number:
  US09/483,143
• Time in Patent Office: 1,517 Days
• Field of Search: 370/229, 370/230, 370/230.1, 370/231, 370/232, 370/233, 370/234, 370/395.4, 370/395.41, 370/465, 370/486, 370/487, 370/493, 370/494, 370/495, 370/535, 370/537, 370/538, 370/540, 375/240, 375/240.01, 375/240.02, 375/240.05, 375/240.07, 375/240.23
• US Class Current: 370/230
• CPC Class Codes: H04N 21/2335 involving reformatting operations of audio signals, e.g. by converting from one coding standard to another details of audio signal transcoding G10L19/173
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 7/52 Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434

Abstract

A multimedia terminal comprising: a first encoder (100) for producing a first bit-stream (107) of a first media type and having a first bit-rate; a second encoder (110) for producing a second bit-stream (112) of a second media type and having a second bit-rate; a multiplexer (120) for combining at least the first (106) and the second (112) bit-streams into a third bit-stream (123). The terminal comprises an input element (130) for receiving preference information (131) coupled to the first encoder (100) and the second encoder (110), said preference information (131) indicating a preferred combination of the first and the second media types in the third bit-stream and affecting the first and the second bit-rates. Thus, the transmission capacity is utilised in a more optimised manner and the proportions of different media types are better adjusted to the purpose of the information transfer.

Claims

1. A multimedia terminal comprising:

a first encoder for encoding a first signal for producing a first bit-stream of a first media type and having a first bit-rate;

a second encoder for encoding a second signal for producing a second bit-stream of a second media type and having a second bit-rate;

a multiplexer for combining at least the first and the second bit-streams into a third bit-stream;

an input element for receiving preference information, said input element being coupled to the first encoder and the second encoder, said preference information indicating a preferred combination of the first and the second media types in the third bit-stream and affecting the first and the second bit-rates;

wherein said first encoder comprises a first control element for receiving first control information, and controlling the first bit-rate according to said first control information;

said second encoder comprises a second control element for receiving said first control information, and controlling the second bit-rate according to said first control information;

said input element is arranged to provide said first control information generated according to said preference information to the first and the second control elements;

the second control element comprises a first feed-back loop, comparison means, and a controller;

said first feed-back loop is arranged to transfer information on an actual averaged bit-rate of the second bit-stream to the comparison means;

said comparison means is supplied with a target average bit-rate, arranged to calculate the difference between the actual averaged bit-rate of the second bit-stream and the target average bit-rate, and to provide the calculated difference to the controller;

said controller is arranged to output a control signal to the second encoder, as a response to receiving said calculated difference; and

said second encoder is arranged to adjust the bit-rate of the second bit-stream according to the received control signal from the controller.

2. A multimedia terminal according to claim 1, comprising

a multiplexer buffer for storing data from the multiplexer for transmission; and

said multiplexer buffer is connected to a second feed-back loop arranged to transfer information on the occupancy level of the multiplexer buffer, said occupancy level indicating the current amount of data stored in the buffer.

3. A multimedia terminal according to claim 2, wherein the second control element is arranged to further adjust the bit-rate of the second bit-stream according to the feed-back information received from the second feed-back loop.

4. A multimedia terminal according to claim 2, wherein the first control element is arranged to further adjust the bit-rate of the first bit-stream according to the feed-back information received from the second feed-back loop.

5. A multimedia terminal according to claim 2, wherein the first control element is arranged to adjust the temporal resolution of video encoding according to the feed-back information received from said second feed-back loop.

6. A multimedia terminal according to claim 5, wherein the multiplexer buffer is provided with a first threshold;

and either of the first and second control elements is arranged to adjust the bit-rate of the corresponding bit-stream, as a response to the multiplexer buffer occupancy level exceeding the first threshold.

7. A multimedia terminal according to claim 6, wherein the second encoder is a speech encoder, and the second encoder is arranged to adjust the bit-rate of the second bit-stream, as a response to the multiplexer buffer occupancy level exceeding the first threshold.

8. A multimedia terminal according to claim 7, wherein the multiplexer buffer is provided with a second threshold for multiplexer buffer occupancy level, said second threshold being higher than the first threshold;

and the first encoder is arranged to adjust the bit-rate of the first bit-stream, as a response to the multiplexer buffer occupancy level exceeding the second threshold.

9. A multimedia terminal according to claim 1, wherein the first encoder is a video encoder;

and the first control element is arranged to adjust the spatial resolution of video encoding according to the control information received from the input element.

10. A multimedia terminal according to claim 1, comprising a video codec and a speech codec, and means for communicating with a mobile communication network.

11. A multimedia terminal according to claim 10, comprising a user interface for inputting the preference information.

12. A multimedia terminal according to claim 11, wherein the user interface comprises a slide switch.

13. A multimedia terminal according to claim 10, comprising means for receiving preference information from the mobile communication network.

14. A protocol for communicating between a first multimedia terminal and a second multimedia terminal, said first multimedia terminal comprising

a first encoder for encoding a first signal for producing a first bit-stream of a first media type and having a first bit-rate;

a second encoder for encoding a second signal for producing a second bit-stream of a second media type and having a second bit-rate;

a multiplexer for combining the first and the second bit-streams into a third bit-stream;

an input element for receiving preference information, said input element being coupled to the first encoder and the second encoder;

said protocol comprising formatted signals for transferring information between the first and the second multimedia terminals; and

a message for indicating the capability of the first multimedia terminal to control the first and the second bit-rates according to the preference information received by the first multimedia terminal, said preference information indicating a preferred combination of the first and the second media types in the third bit-stream and affecting the first and the second bit-rates; and

wherein said first encoder comprises a first control element for receiving first control information, and controlling the first bit-rate according to said first control information;

said second encoder comprises a second control element for receiving said first control information, and controlling the second bit-rate according to said first control information;

said input element is arranged to provide said first control information generated according to said preference information to the first and the second control elements;

the second control element comprises a first feed-back loop, comparison means, and a controller;

said first feed-back loop is arranged to transfer information on an actual averaged bit-rate of the second bit-stream to the comparison means;

said comparison means is supplied with a target average bit-rate, arranged to calculate the difference between the actual averaged bit-rate of the second bit-stream and the target average bit-rate, and to provide the calculated difference to the controller;

said controller is arranged to output a control signal to the second encoder, as a response to receiving said calculated difference; and

said second encoder is arranged to adjust the bit-rate of the second bit-stream according to the received control signal from the controller.

15. A protocol according to claim 14, the protocol further comprising a message for delivering the preference information from the second multimedia terminal to the first multimedia terminal.

16. A method for controlling multiplexing of a multimedia transmission comprising the steps of:

encoding a first signal for producing a first bit-stream of a first media type and having a first bit-rate;

encoding a second signal for producing a second bit-stream of a second media type and having a second bit-rate;

combining at least the first and the second bit-streams into a third bit-stream;

receiving preference information, said preference information indicating a preferred combination of the first and the second media types in the third bit-stream; and

adjusting the first and the second bit-rates according to the received preference information;

wherein the step of encoding the first signal is accomplished by a first encoder having a first control element for receiving first control information, the method including a step of controlling the first bit-rate according to said first control information;

the step of encoding the second signal is accomplished by a second encoder having a second control element for receiving said first control information, the second control element comprising a first feed-back loop, comparison means, and a controller;

the method including a step of controlling the second bit-rate according to said first control information;

the method further comprises steps of transferring, via said first feed-back loop, information on an actual averaged bit-rate of the second bit-stream to the comparison means;

supplying to said comparison means a target average bit-rate, and calculating a difference between the actual averaged bit-rate of the second bit-stream and the target average bit-rate, and providing the calculated difference to the controller;

outputting a control signal via said controller to the second encoder, as a response to receiving said calculated difference; and

adjusting the bit-rate of the second bit-stream by said second encoder according to the received control signal from the controller.